psych statistics 2a-exam 1

A population of N = 10 scores has µ = 21 and σ = 3. What is the population variance? 7 100 2 9

9

A distribution of scores is positively skewed. Which is the most probable order, from smallest to largest, for the three measures of central tendency? Mean, median, mode Mode, median, mean Mean, mode, median Median, mean, mode

Mode, median, mean

A population of N = 5 scores has a mean of µ = 20 and a standard deviation of σ = 4. Which of the following is the correct interpretation of the standard deviation? The average distance of scores from the mean of µ = 20 is 5 points. The average distance of scores from the mean of µ = 20 is 1 point. The average distance of scores from the mean of µ = 20 is 4 points. The average squared distance of scores from the mean of µ = 20 is 4 points.

The average distance of scores from the mean of µ = 20 is 4 points.

If a sample has an even number of scores, at least one individual will have a score exactly equal to the median. True False

false

Students in an introductory art class are classified as art majors and non-art majors. Which scale of measurement is being used to classify the students? nominal ordinal interval ratio

nominal

A datum is different from data as a term in that a datum refers to _____. a sample. a population. one score. a set of scores.

one score

A researcher uses an anonymous survey to investigate the social media habits of American college students. Based on the set of 300 surveys that were completed and returned, the researcher finds that students spend an average of 2 hours each day using social media. The set of 300 students who returned surveys is an example of a _____. parameter. statistic. population. sample.

sample

The average verbal SAT score for the entire class of incoming college freshmen in the United States is 530. However, if a sample of 20 incoming college freshmen is randomly selected from the United States, it is likely that this sample's average verbal SAT score will not be exactly 530. This is consistent with the concept of _____. statistical error. inferential error. sampling error. descriptive error.

sampling error.

The mode is similar to the median as a measure of central tendency in that _____. its value must correspond to an actual score in the data set. it balances the distance between scores above and below its value. it represents the middle of a distribution. there are no symbols used to differentiate between whether its value(s) pertains to populations or samples.

there are no symbols used to differentiate between whether its value(s) pertains to populations or samples.

The range is considered to be a relatively crude measure of variability. True False

true

Using the frequency distribution table below, what is the proportion of individuals that scored a 4? X f 6 4 5 3 4 7 3 2 2 2 1 2 .2 .7 .35 .1

.35

What is the value of Σ(X + 1) for the scores 2, 3, 5? 6 9 11 13

13

What is the range for the following set of scores obtained for a discrete variable for which 0 is not a possible score? Scores: 5, 7, 9, 13 4 points 5 points 8 points 13 points

8 points

Why do deviation scores have to be squared before calculating the standard deviation? Squaring is necessary when calculating inferential statistics. If deviation scores are not squared, then the average distance from the mean will always equal 0. Squaring deviation scores allows for degrees of freedom to be calculated. If deviation scores are not squared, then the interquartile ranges are incalculable.

If deviation scores are not squared, then the average distance from the mean will always equal 0.

For a perfectly symmetrical distribution, which relationship is always true? mean = median mean = mode median = mode mean = median = mode

mean = median

You are instructed to square each score and subtract four points from the sum of these squared scores. How would this set of instructions be expressed in summation notation? Σ(X 2) - 4 (ΣX)2 - 4 (X - 4)2 ΣX 2 - 4

Σ(X 2) - 4

Which of the following actions will always change the value of the mean? changing the value of one score adding a new score to the distribution removing a score from the distribution adding the same amount to each score in a distribution.

changing the value of one score

It is possible to have a distribution of scores where no individual has a score exactly equal to the mean. True False

true

The amount of time that it takes a person to solve a problem is an example of a(n) _____ variable. independent nominal continuous discrete

continuous

For an experiment comparing the effectiveness of two different teaching methods for improving the social skills of autistic children, the dependent variable would be the _____. experimental methodology. autistic children. teaching methods used to teach social skills. levels of improvement in social skills among autistic children.

levels of improvement in social skills among autistic children.

A sample of n = 6 scores has a mean of M = 5. One person with a score of X = 19 is added to the distribution. What is the mean for the new set of scores? M = 5 M = 6 M = 7 M = 8

m=7

A tenet of the scientific method is that _____ allow researchers to examine mental processes and behavior in an empirical, scientific manner. correlational research studies experimental research studies operational definitions constructs

operational definitions

What is the median for the following set of scores? Scores: 1, 5, 11, 12, 20 5 11.5 11 8

11

What is the value of SS (sum of squared deviations) for the following population? Population: 1, 1, 1, 5 2 7 12 6

12

Which set of scores below has the smallest standard deviation? 11, 17, 31, 53 5, 11, 42, 22 145, 143, 145, 147 27, 105, 10, 80

145, 143, 145, 147

What is the median for the data represented in the histogram below? 1.80 3 2 1.50

2

A sample of n = 10 scores has a mean of M = 3. What is ΣX for this sample? 30 3.33 .3 13

30

Which statement below must be false regarding a distribution of scores? 75% of the scores are above the mean 75% of the scores are above the median 75% of the scores are above the mode 75% of the scores are the same value as the mode

75% of the scores are above the median

Which of the following statements is correct regarding a biased statistic? A biased statistic occurs when the average value of a statistic overestimates the corresponding population parameter. A biased statistic occurs when the average value of a statistic underestimates the corresponding population parameter. A biased statistic occurs when the average value of a statistic is equal to the corresponding population parameter. A biased statistic occurs when the average value of a statistic either underestimates or overestimates the corresponding population parameter.

A biased statistic occurs when the average value of a statistic either underestimates or overestimates the corresponding population parameter.

Which statement below is true? It is possible for a distribution of scores to have two means. It is possible for a distribution of scores to have two means or two medians. It is possible for a distribution of scores to have two modes. It is possible for a distribution of scores to have two medians or two modes.

It is possible for a distribution of scores to have two modes.

One sample is selected to represent scores in treatment 1 and a second sample is used to represent scores in treatment 2. Which set of sample statistics would present the clearest picture of a real difference between the two treatments? M1 = 36, M2 = 40, and both variances = 43 M1 = 36, M2 = 40, and both variances = 6 M1 = 38, M2 = 40, and both variances = 43 M1 = 38, M2 = 40, and both variances = 6

M1 = 36, M2 = 40, and both variances = 6

The mode is the only measure of central tendency that is appropriate to utilize for a variable measured with which scale of measurement? ordinal nominal interval ratio

nominal

A set of 5 scores has SS = 20. If the scores are from a sample, the sample variance is ____. If the scores comprise a population, the population variance is ____. s2 = 5; σ2 = 4. s2 = 4; σ2 = 5. s2 = 5; σ2 = 5. s2 = 5; σ2 = 5.

s2 = 5; σ2 = 4.

In order to determine if 10 points below the mean on an exam is an extreme negative score, the _____ needs to be known. mode standard deviation range median

standard deviation

A person's phone bills for the last three months were $20, $75, and $55, respectively. What was the mean average amount for the three phone bills? $60 $50 $55 $65

$50

What is the mode for the population of scores presented in the frequency distribution table below? X f ​5 1 ​4 4 ​3 3 ​2 4 ​1 2 ​ 3 4 2 2 and 4

2 and 4

What is the variance for the following population of scores? Scores: 2, 5, 6, 3 2.5 3.33 4 5

2.5

A population has a mean of µ = 15. If 6 points are added to each score, what is the mean for the new distribution of scores? µ = 9 µ = 15 µ = 21 µ = 11

21

What is the mean for the population of scores presented in the frequency distribution table below? X f ​8 3 7 3 ​6 0 ​5 2 ​4 1 3 2 2 2 1 3 ​ µ = 3 µ = 4.50 µ = 5 µ = 4

4.50

What is the percentile rank for a score of 4 in the frequency distribution table below? X f 6 4 5 5 4 1 3 3 2 6 1 1 45th 60th 50th 55th

55th

A researcher conducts a research study to examine how a new treatment for anxiety compares in efficacy to a standard therapy. This researcher assigns clinically anxious participants to either a new treatment or standard treatment for six months, and then observes anxiety levels following. The researcher finds that the new treatment group has an average anxiety score of M = 50 with a standard deviation of s = 5 following treatment, whereas the standard treatment group has an average anxiety score of M = 60 with a standard deviation of s = 6. Which statement below is consistent with how these results would be reported in an APA style journal article? Clinically anxious individuals who received a new treatment displayed greater anxiety levels (M = 60.00, SD = 6.00) than clinically anxious individuals who received a standard treatment (M = 50.00, SD = 5.00). Clinically anxious individuals who received a new treatment displayed less anxiety levels (M = 60.00, SD = 6.00) than clinically anxious individuals who received a standard treatment (M = 50.00, SD = 5.00). Clinically anxious individuals who received a new treatment displayed less anxiety levels (M = 50.00, SD = 5.00) than clinically anxious individuals who received a standard treatment (M = 60.00, SD = 6.00). Clinically anxious individuals who received a new treatment displayed greater anxiety levels (M = 50.00, SD = 5.00) than clinically anxious individuals who received a standard treatment (M = 60.00, SD = 6.00).

Clinically anxious individuals who received a new treatment displayed less anxiety levels (M = 50.00, SD = 5.00) than clinically anxious individuals who received a standard treatment (M = 60.00, SD = 6.00).

Which statement below regarding populations is true? Populations typically are small in size. Populations cannot consist of non-human animal research subjects. The experimental research method should be used to examine populations. It usually is challenging to obtain data from every person in a population.

It usually is challenging to obtain data from every person in a population.

If a set of exam scores forms a negatively skewed distribution, what can you likely conclude about the students' scores? Most of the students had relatively high scores. Most of the students had relatively low scores. About an equal number of students had relatively high and relatively low scores. It is not possible to draw any conclusions about students' scores with this information.

Most of the students had relatively high scores.

The relationship between a statistic and a sample is the same as the relationship between _____. a sample and a population. a statistic and a parameter. a parameter and a population. descriptive and inferential statistics.

a parameter and a population.

In order for a researcher to obtain a random sample, they need to specifically do which of the following things? rule out confounding variables ensure that each person in the population has an equal chance of being selected for the sample make certain that results are valid make sure that each participant has an equal chance of being assigned to each experimental condition

ensure that each person in the population has an equal chance of being selected for the sample

Sarah is conducting a research study in which one group of participants consume one cup of coffee, whereas another group of participants consume two cups of coffee. Then, she assesses attention levels of these participants following coffee consumption. This is an example of a(n) _____ research study. descriptive correlational quasi-experimental experimental

experimental

For a severely skewed distribution, the mean often provides a better measure of central tendency than the median or the mode. True False

false

What additional information is obtained by measuring two individuals on an interval scale compared to an ordinal scale? whether the measurements are the same or different the direction of the difference the size of the difference whether the measurements are reliable

the size of the difference

In general, more information is lost in a grouped frequency distribution table that has class intervals with a width of 10 than a grouped frequency distribution table that has class intervals with a width of 5. True False

true

Multiplying every score in a sample by a constant value will change the value of the standard deviation. True False

true

Participants reporting the number of cell phones they have owned in their lifetime would be an example of a discrete variable. True False

true

Random assignment helps to strengthen causal inferences within an experiment by ruling out potential confounding variables otherwise introduced to an experiment due to individual differences in participants True False

true

The goal for an experiment is to examine whether changes in one variable are responsible for causing changes in a second variable. True False

true

The median is the value in a distribution of scores that separates the lowest 50% of scores from the highest 50% of scores. True False

true

Using polling results from a sample of 100 registered voters in Iowa to predict the outcome of a statewide election set to take place one week later is an example of using inferential statistics. True False

true

Under which circumstance below is the median likely to be a better measure of central tendency than the mean? with a symmetrical distribution with an extremely skewed distribution when the data consist of nominal measurements when the data come from a continuous variable.

with an extremely skewed distribution

For the following scores: a. Construct a frequency distribution table. b. Sketch a histogram of the frequency distribution. 1, 2, 3, 1, 1, 4, 2 1, 5, 6, 2, 2, 1, 3

x f 1 5 2 4 3 2 4 1 5 1 6 1

On an exam with a mean of µ = 80, a person scores X = 90. Which of the following values for the standard deviation would position this person highest within the class? σ = 2 σ = 5 σ = 10 σ = 15

σ = 2